Circuit closing and breaking arrangement for teleprinters



K. WEBER ETAL 3,005,040

CIRCUIT CLOSING AND BREAKING ARRANGEMENT FCR TELEPRINTERS Filed May l,1957 :El annnosnnnann 5 Oct. 17, 1961 INVEIVTORS.;v KAREL WEEE/I7 andJAIPUSLAV VANA AGENT.

United States Patent() The present invention relates to a circuitclosing and breaking arrangement for teleprinters which both operate byway of a direct line and can be connected to a manual or automaticteleprinter exchange.

In the case of a direct connection between two teleprinters, theswitching on and oft of these installations has heretofore been effectedas follows: A special battery or power supply Vis interposed in theseries circuit connection between the two teleprinter stations by way ofthe longdistance line for the purpose of actuating the receiving magnetsof the two teleprinters. If printing is not being carried out on theteleprinters, a spacing current of 40 ma. flows -in the above describedcircuit. ln this inoperative condition, the teleprinter motors areswitched off. To start operation of the teleprinter installations, thecalling key of the home or sending teleprinter is depressed momentarily.As a result of this operation, the spacing current is interrupted and amechanical circuit closing and breaking device located in theteleprinter is closed. The mechanical switch in the opposite orreceiving teleprinter is also actuated by this operation.V A specialcontact connects the motor of the teleprinter to the power supply andthe installations are ready for operation. Through constantinterruptions in the keyed letter combinations, a toothed wheel providedin the switch is repeatedly brought to the inoperative position and doesnot influence the disconnecting contact of the motor.

When the teleprinter correspondence has been terminated, the toothedwheel actuates the disconnecting contact after 45 seconds, so that thedisconnecting contact opens and the teleprinter motors are againdisconnected from the power supply. Apart from the long idling time of45 seconds for the motors after every call, there is a furthercomplication resulting from this circuit closing and breaking device.The speeds of the two teleprinters have different time constants, sothat the home teleprinter motor is still running while the oppositeteleprinter has already switched o its motor. If printing is nowcontinued on the teleprinter ywhich is still running, the distant -motormust first start again and wrong letters are printed during the intervalbefore the latter has reached its proper speed.

The mechanical circuit closing and breaking device -itself is a specialsupplementary device of the teleprinter and must be fitted where thereis a direct connection of the kind described. If the teleprinter isconnected to manual or automatic teleprinter exchanges, the mechanical'circuit closing and breaking device must be put out of action. Thecircuit closing and breaking device consists of a large number ofcomplicated component parts and the design of the teleprinter must takeinto account the drive and the space required for the circuit closingand breaking device. y

In addition to the above described existing arrangement for switchingthe two teleprinters on and off, other arrangements exist which operateon an acoustic or optical signalling system. In these instances not onlyis there the drawback of requiring constant supervision at the stations,but Special manual changeovers are necessary for switching on the motorand producing the calling condition. Acoustic signals are difficult todistinguish if several teleprinters are contained in one room and inaddivce tion they may not be heard. Moreover, these signallingarrangements require special supplementary apparatus which must bemounted outside the teleprinter.

All these drawbacks are eliminated by the present invention whichprovides a circuit Vclosing and breaking arrangement by which improvedteleprinter communication is rendered possible. A direct teleprinterconnection can be established with this arrangement and in addition itcan be connected to a manualor automatic teleprinter exchange.

The entire arrangement, including the current supply, may be produced asan independent apparatus or may be `in the form of a structural unitcontained in the teleprinter itself. In the form of an independentapparatus, the dimensions of which are about 250 x x 140 mm. and theweight about 3.8 kg., the arrangement offers several advantages. Thus,for example, all conventional types of teleprinters can be connectedwithout the teleprinters requiring special supplementary devices for adirect connection. Apart from its use for conventional teleprintercommunication, this independent apparatus may also be employed for localtesting of teleprinters, as, for example, in the factory test shops orin repair workshops. It is also very suitable yas a portable apparatusfor outside use. v

The appropriate change in the circuit arrangement for each individualmethod of operation, whether by direct connection or connection to amanual or automatic teleprinter exchange, is elected by means of acombination plug or a rotary switch.

If there is a direct connection between two teleprinters, depressing thecircuit-closing key, causes both the home and the opposite teleprinterto beimmediately switched on. A further advantage of this invention isthe fact that when the teleprinter traic has been terminated, both theteleprinters are immediately switched off by depressing thecircuit-breaking key. The one-way and two-way circuit closing andbreaking thus achieved is of great value for more rapid operation.|Thus, one station can switch on both teleprinters by the depression ofthe circuit-closing key and switch oil both teleprinters at the end ofthe transmission by the depression of the circuit-breaking key, -or bothteleprinters are switched on at one station and switched off at theother station. Consequently, the new circuit-closing and breakingarrangement has the advantage that the subscriber whose machine lastprints a message can also break the existing connection by depressingthe circuit-breaking key independently of the call.

A further novel feature of the circuit closing and breaking arrangementembodying the invention consists in that, where there is a directconnection, optical signalling by means of Morse signals is alsopossible in addition to the communication in Writing through theteleprinters. If one or the other of the teleprinters is not ready foroperation because of some fault or trouble, emergency operation by meansof Morse signals can be carried out when the circuit-closing key isdepressed and the signal lamp is lit up.

The direct connection previously described requires a current of about40 ma. for satisfactory operation of the teleprinters. Owing to thishigh current intensity, which also ows through the long-distance line,the range of this teleprinter connection is comparatively short. Thus,the winding of a polarized telegraph relay can be energized in place ofthe teleprinter receiver previously mentioned inconnection with thecircuit. The high operating sensitivity of this relay enables the linecurrent intensity to be reduced from 40 ma., which has been previouslyused, to 10 ma, whereby a Ifar greater range is obtained for theteleprinter connection. I'he contact of the polarized relay controls theteleprinter receiver at a current intensity of 40 ma. by way of a'rectied voltage from the same transformer. The circuit-closing andbreaking functions are the same whether or not a telegraph relay isinterposed inthe circuit.

The above, and other objects, features and advantages of the invention,will be apparent in the following detailed dcription of an illustrativeembodiment thereof which is to be read in connection with theaccompanying drawing showing a wiring diagram of the circuits at twoteleprinter Stations that may be connected directly together orconnected through a manual or automatic exchange.

- Referring to thev drawing in detail, it will be seen that thecircuitry at 'each of the two stations 1 and 2 includes two contacts G1and G2 by which the primary L0 of a feeding transformer T is adaptedto-be connected to A.C. power supply lines. When contacts G1 and G2 areclosed, the alternating current passing through primary L inducesYalternating currents in four secondary windings L1, L2, L3, L4 Voftransformer T. The currents obtained Vin the windings L1, L2, L2, arerectified in rectiers Q1,

Q2, Q3, respectively, 'the purposes of which *will be explained later.The rectiiiers Q1 and Q2 give a D.C. voltage of 60 volts each. Ifconnected in series, the total output voltage of the two -rectiers Q1and Q2 will be 120 volts. The fourth secondary winding 14 of feedingtransformer T serves as an A.C. source for two signal lamps S1 and S2.The rst' lamp S1 remains lighted so long as there is a current inducedin the winding L., and thus indicates that the teleprinter station isconnected to the power-supply network. The second lamp S2 is lightedonly if the contact Ez'is in its on-position. This contact is controlledby a relay E, as will be explained later. Y

Each station further comprises a signal transmission circuit TRrepresented diagrammatically by its two terminals a, b and a signalreceiver circuit RE represented also by its two terminals c and W2.Details of the transmission 'circuit TR'and of the receiver circuit REare not illustrated because these two circuits may have arrangementsWell'known in the art. Each station has aV dialing device DL for thetransmissionfof dialing pulses when the two stations 1 and 2 are to beconnected indirectly over Vva teleprinter exchange (EX). Each'stationfurther has ve relays A, B, C, D,'E. Relay A is a polarized relay whichbecomes energized if it receives a voltage of 60 Volts of a certainnpolarity and which releases thereafter only if it has received avoltage of 120 volts of'opposite Y polarity. Moreover, relay A has twowindings a1 and a2 and is operated if at least one of its windingsreceives a voltage in the above indicated manner. Relay E is anonpolarized relay, but also has two windings e1, e2 and is thereforeenergized -if at least one of these windings carries a sufficientenergizing current. The other three relays B, C, D are normal relays andhave only one winding each. Relay A controls a contact A1, relay BVcontrols four contacts` B1, B2, B3 and B4, relay C Acontrols fourcontacts C1, C2, C3 and C4, relay D'controls Vtwo contacts D1 and D2,and relay-E controls two contacts E1 and E2, the latter of which -hasVbeen already mentioned above. Each station has ,a circuit-making keywhich is represented in the drawing by its two coupled contacts vt1 andvt2, and a circuit-breaking key represented byeits four coupled contactskt1, kt2, kt3, kz4, all of which are therefore operated simultaneously.The keys themselves are not shown be- Y cause their mechanicalarrangement may be of any known kind commonly used in multiple switches.The teleprinter motor is indicated at P.

Each station has eight terminals or sockets`4, 5, 6, 7, 8, 9, 10, 11, 12which may be interconnected in two different ways, depending on whetherthe two stations 1 and 2 are to be connected directly to each other,that is without interposition` of the teleprinter exchange (EX), orindirectly, over such exchange.

1) Direct connection of two stations It itis desired to adapt Ystations1 and 2 for adirect connection over a two-wire teleprinter line F1, F2,it is necessary to connect sockets 6 with 7, 4 with 8, and 10 with 12 instation 1 and similarly in station 2, as in- Y dicated by broken lineson the drawing. After doing so,

the two stations 1 and 2 are ready for a direct connection over the lineF1, F2 although no currentas yet passes through said line. ,v

If one of the subscribers or stations, for instance station 1, wants toestablish communication with station 2, the circuit-making key isoperated at station 1, thereby swiching over the contacts vt1 and vt2 instation 1. The contacts vt1 and vt2 in the called station 2 remain, ofcourse, in unchanged position. The switching over of contact vt1 instation 1 is of no importance for the direct connection between station1 and stationZ and its function in the case of an indi-rect connectionover a teleprinter exchange Will be explained later.

The operation ofV contact vt2 in station 1 opens the way for theelectric current supplied by the rectifier Q1 into the following circuity( 1) which is identified by referring to the reference numerals of thecomponents successively passed through by the current:

As is apparent in the above-description of circuit (1), both the relay Ain station 1 and the relay A in station 2 become energized and switchover Ytheir contacts A1 thus crlosirzlg the following circuit,(2) instation 1 and in station Thus the relays C in station 1 and station 2also become energized and switch over their contacts C1, C2, C3 and C4.The closing of contact C1 renders ineiective the dialing device DL whichis of no use for a direct connection between the two stations 1 and 2and which, in the case of such direct connection, could only produceundesired eifects if operated by mistake. The contact C2 closes afurther circuit (3):

The current passing through this circuit (3) energizes the relay D whichswitches on the two contacts D1 and D2 and thus starts the teleprintermotor P. Contacts C3 and C1 w h1ch were also switched over by relay -Cchange the circuit (1) connecting station 1 with station 2 into thefollowing circuit (4):

Circuit (4)--minus Q24(station 1)-B3-6-'77 wire line F1, F2 until thecircuit-breaking key with its contacts kt1, kt2, kt3 and kt4 isoperated, as will be explained later. As long as no pulses of codecombinations are transmitted over the line F1, F2, this line istraversed by a spacing current supplied by the D C. source Q2. Thiscurrent may be adjusted by the Variable resistor R4 and can be measuredby a milliamnieter M after opening the contact t1 which normally shuntsthe milliammeter M in order to protect it against repeated changes ofcurrent durrent during the transmission of code combinations.

The transmission of the code `combinations Iby the transmission circuitTR in station l and their reception by the receiver circuit RE instation 2 is performed in the usual manner, as in any known teleprinter.

If the operator of station l or of station 2 wants to break theconnection established between the two stations over the line F1, F2, hedepresses the circuit breaking key in his station and thus switches overthe contacts kz1, kz2, ktg and kt. In doing so, circuit (4) isinterrupted by opening the contact kt2, whereas relay B becomesenergized by the current flowing through the following circuit (5):

In consequence of the closing of circuit (5), relay B switches over itsfour contacts B1, B2, B3 and B1. In the case of the contacts B1 and B2this change has no particular effect at that moment, but the switchingover of contacts B3 and B4 causes the line F1, F2 to receive a currentsupplied by the two sources Q2 and Q3 connected in series and thusyielding a voltage of 120 volts. Moreover, the polarity of this voltageof 120 volts is opposite to the polarity of the Voltage of 60 voltspreviously applied to the line F1, F2 and also opposite to the polarityof the source Q2 of the other station. Thus the polarized relays A arereleased by the diiference of the two voltages both in station 1 and instation 2 and their contacts A1 revert to the open position shown in thedrawing. Circuit (3), which has hitherto kept the relay D in energizedcondition, is interrupted at the contact A1, relay D releases itscontacts D1 and D2 and the teleprinter motor P is stopped. Both stationl and station 2 return to their idle condition.

it is to be noted that the contact C1 also returns to its initialposition shown in the drawing. This is of irnportance for establishingconnection between the two stations l and 2 at the next opportunity. Infact, if the transmission circuit TR remains interrupted after the endof the previous transmission, contact C1 ensures the initial closing ofthe above described circuit (l) when the next call is made.

(2) Indirect connection of stations 1 and 2 over a teleprnter exchangeFor this purpose the previously mentioned pairs of sockets or terminals6 and 7, 4 and 8, 10 and 12 must be disconnected and, instead thereof,the following sockets must be connected: 4 with 7, and 9 with 11. Aslong as a station is in its idle condition a rest current passes throughthe following circuit (6):

This rest current of approximately l0 ma. passing through circuit (6)energizes relay E. The second contact E2 controlled by this relay Eextinguishes the signal lamp S2. The rest current is, however, too weakto put into operation the signalling device in the teleprinter exchange.

If one station wants to call another station over the teleprinterexchange, the operator of the calling station depresses thecircuit-making key, that means he switches over the contacts V21 andvt2. The contact vt2 is of no importance in this case, but the contactvt1 closes the following circuit (7):

Circuit (7)-minus Q1-C2-vz1--9-11--kt4-B- Y plus Q1 The current passingthrough circuit (7) energizes relay B which, once it has been operated,holds itself in energized condition by its contact B2 which closes thefollowing circuit (7a):

Circuit (7a)minus Q1-C2-B2-9-i1-kt4-B- plus Q1 Relay B switches over allits contacts mentioned above, among others the contact B1 whichincreases the current passing through the circuit (6) by reducing theresistance which this current has to overcome. In fact, said current hadto pass previously between the components a1 and kt2 through thefollowing components: a2 (120 ohms)-R3 (10,000 ohms)-e2 (3800 ohms),whereas it can now ow between the components a1 and kt2 also over aparallel line rendered eifective by the closing of the contact B1,namely the line B1-e1 (350 ohms) so that circuit (6) is now changed intothe following circuit (8):

This reduction of ohmic resistance increases the current from l0 ma. to40 ma.

In the case of a manual exchange, the increased current of 40 ma. setsinto operation the calling signal in the exchange and the exchangeoperator reverses the polarity of the current by the answering plug,asks the calling subscriber in the usual manner to what station he wantsto be connected and eects the desired connection.

In the case of an automatic exchange the above mentioned increasedcurrent of 40 ma. sets into operation the line finder and causes a breakof the current for 30 milliseconds. This break releases relay E whichhitherto remained energized by its low-ohmic winding e1 and from now oncannot be energized any more, because after itsV release the contact E1short-circuits the winding e1. The contact E2 controlled by the relay Eextiuguishes the signal lamp S2 and thus informs the calling subscriberthat he may begin the selection of the desired called station. Theselection is carried out by interrupting the current owing through theabove described circuit (8). The interruptions are elfected by operatingthe dial DL in known manner. If the desired connection has beenestablished, the teleprinter exchange reverses automatically thepolarity of the current passing through the line F1, F2 and the relay Ain the calling station switches over its cintact A1 thus closing theabove described circuit (2). As in the case of the previously describeddirect connection, relay C is operated by circuit (2) and thereafterrelay D by circuit (7a) thus releasing relay B, but before this happens,two other contacts C1 and C4 controlled by relay C change circuit (8)into the following circuit (9):

Circuit (9)-Teleprinter exchange (EX)-F1a-TR The teleprinter motor Vl?is started by the contacts D1 and D2l controlled by the relay D. v

In the called station, the reversal of polarity of the current eiectedby the exchange operates the polarized relay A which closes the circuit(2,) whereafter all the operations which have been described above forthe calling station develop identically in the called station.

lf the subscriber wants to abandon the selection before he has obtainedconnection through the exchange (manual or automatic), he depresses thecircuit-breaking key which by its contact kt., breaks the circuit (6a)and releases relay B.

If the subscriber wants to terminate the connection after the connectionbetween the calling and the called station has been established throughthe teleprinter exchange, he holds the circuit-breaking key depressedand thus its contacts kil, kt2, kf and kt.; opened for a longer time. Inthe case of a manual exchange this long-lasting interruption givesnotice to the exchange operator that the connection is to be terminatedwhereafter the operator interrupts the connection in known manner,reverses the polarity of the current passing through the line F1, F2 andthus causes relay A to release. This interrupts the circuits (2) Vand(3) in the above described manner so that only a rest current of l ma.continues to flow over the circuit (6). In the case of an automaticexchange, the change of polarity of the current passing through the lineF1, F2 is eiected automatically in known manner when the depression ofthe circuit-breaking key in the subscribers station has lasted apredetermined time.

The crossing dotted lines F1, F2 in the exchange indicated at (EX) inthe drawing denote that the lines F1, F2 may either continue to runwithout interruption, as in the case of a Vdirect connection betweenstations 1 and 2, or that they may be broken in this region and a manualor automatic teleprinter exchange interposed between them as explainedabove.

When there is a direct connection between stations l and 2, as describedabove, signalling between the two stations may be conducted while theteleprinters are inoperative. Such signalling is eiected by depressingthe circuit closing key which closes the contacts vtl and vt2 operatedthereby, so that the relay E is energized to open its Contact E2 andthereby extinguish lamp S2. When the circuit closing key is released,relay E is deenergized to again close contact E2 and thereby causeillumination of lamp S2. Thus, by suitably regulating the rhythm withwhich the circuit closing key is repeatedly depressed and released, theilluminating and extinguishing of the lamp S2 can be madeV to constitutesignals in the Morse code or otherwise.

Although an illustrative embodiment of the invention has been describedin detail herein with reference to the accompanying drawing, it is to beunderstood that the invention is not limited to that precise embodiment,and that various changes and modiiications may be made therein withoutdeparting from the scope or spirit of the invention, except as definedin the appended claims.

We claim: 1. A circuit closing and breaking arrangement for teleprinterscomprising switching circuits connected to a plurality of terminals andincluding a polarized relay for each teleprinter station, key operatedcircuit closing means for operating said polarized relay, a 60 voltcircuit closed by operation of said polarized relay and control meansfor a motor of the associated teleprinter including 'an auxiliary relayoperated by closing of said 60 volt circuit, and switch means engageablewith said terminals and having at least two diierent positions, saidswitching circuits serving to operatively connect the respectivecircuits of teleprinters at two directly connected stations in one ofsaid positions of the switch means and to operatively connect thecircuits of one of the teleprinters to an exchange in another of saidpositions of the switch means. g

2. A circuit closing and breaking arrangement as in claim 1; whereinsaid switching circuits further include a second relay operatedwith saidauxiliary relay, a circuit for'carrying a spacing current for theassociatedV teleprinter and being under the control of said second relaywhen said switch means is disposed for directly connecting theteleprinter stations; and means for adjusting said spacing currentincluding a variable resistor interposed in said circuit for carryingthe Spacing current, a milliammeter for measuring the spacing current,and a keyoperated switch normally short-circuiting said milliammeter.

3. A circuit closing and breaking arrangement for teleprinters as inclaim 2; wherein said switching circuits further include a volt circuitof opposite polarity relative to said 60 volt circuit, a key-operatedcircuitbreaking switch effective, upon operation, to connect said 120volt circuit of opposite polarity to said polarized relay, in place ofsaid 60 volt circuit, to eect change-over or said polarized relay andcorresponding release of said second and auxiliary relays, thereby tointerrupt the circuit'for carrying a spacing current and to haltoperation ofthe teleprinter motor, respectively.

4. A circuit closing and breaking arrangement for teleprinters as inclaim 3; further comprising a signal controlling relay connected withsaid polarized relay when said switch means is disposed for connectionto an exchange, and circuit means then controlled by said keyoperatedcircuit closing means to increase the current in the line to 40 ma. foroperating said signal'controlling relay, in the case of a manualexchange, and the line nder, in the case of an automatic exchange, andfurther being operative to cause a reversal of polarity in said lineafter an interval of 30 msec.

5 A circuit closing and breaking arrangement for teleprinters as inclaim 4; wherein said reversal of polarity is effected by the operator,in the case of a manual exchange, to start theteleprinter at the callingstation and to permit enquiry as to the station to be called, whereas,in the case of an automatic exchange, said signal controlling relayreleases to signalize that the circuits are in condition for the dialedselectionV of the receiving station, while the automatic exchange causesthe reversal of polarity following connection to the desired receivingstation.

6. A circuit closing and breaking arrangement for teleprinters as inclaim 5; whereinyin the case of connection toY an exchange, initialoperation of said circuitbreaking switch causes interruption ofthe'conne'ction to the desired receiving station before the latteranswers, and further operation of said circuit breaking switch causesopening of the circuit of said polarized relay and of said signalcontrolling relay to terminate the connection with the receiving stationby reversing polarity of the line current, in the case of an automaticexchange, so that only a supervising current thereafter flows throughthe line, and, in the case of a manual exchange, to signal to theoperator that the connection is to be disrupted.

7. A teleprinter station comprising, in combination, a plurality ofterminals, switch means engageable with said terminals and operativetoconnect the latter in rst and second positions, a plurality of mutuallycoupled circuitmal'n'ng contacts, a plurality ofV mutually coupledcircuitbreaking contacts, a first polarized relay controlling a contact,a second relay controlling a plurality of contacts, circuit meansselectively operating said second relay by way of said contact of therst relay and by way of one of said circuit-breaking contacts, when saidswitch means connects said terminals in said one position, and furtheroperating said second relay by way of one of said circuitmaking contactswhen said switch means connects the terminals in said second position,transmission line means connected to said terminals for selectivelyconnecting theV teleprinter with a teleprinter exchange and directlywith another teleprinter station'when said terminals are connected inSaid rst and second positions, respectively, a

parallel line closed by one of said contacts of the second relay toincrease the rest current flowing through said transmission line meanswhen the latter connects the teleprinter to a teleprinter exchange, andmeans connected to two other contacts of said second relay to increasethe voltage and reverse the polarity of the current owing in saidtransmission line means when the latter connects the teleprinter stationdirectly to another station.

8. A teleprinter station as in claim 7; further comprising a parallelline including another of said contacts controlled by said second relayand operative to shunt said circuit-making contact through which saidsecond relay is operated when said terminals are connected in saidsecond position.

9. A teleprinter station as in claim 8; further comprising a third relaycontrolling a plurality of contacts and being operated by said contactcontrolled by said rst relay, a dialing device, one of said contactscontrolled by said third relay being eiective to render inoperative saiddialing device, a teleprinter motor, a fourth relay controlling contactsfor respectively starting and stopping said motor, and circuit means foroperating said fourth relay including another of said contactscontrolled by the third relay.

References Cited in the file of this patent UNITED STATES PATENTS1,791,587 Vernam Feb. 10, 1931 1,921,799 Benjamin Aug. 8, 1933 2,283,410Bonorden May 19, 1942

